Tsikada and Parus

Navigation information is derived from Doppler-shifted VHF transmissions (approximately 150 and 400 MHz) of satellite position and orbital data (References 441-442). By acquiring fixes from several satellites, a user's location can be calculated with an accuracy of 100 m (Reference 443). The time needed to ascertain one's position is dependent upon the user's latitude and the number of operational spacecraft in orbit. Normally, ten first-generation Russian satellites are transmitting navigational signals, permitting accurate location determination within 1-2 hours.

These ten spacecraft are deployed in two complementary constellations. The older constellation (first launch in 1974 with Kosmos 700) consists of six satellites distributed in orbital planes spaced 30 degrees apart. This network with Parus satellites (aka Tsikada-M) is never explicitly referred to by Russian officials and is primarily dedicated to the support of military forces. A virtually identical civilian navigation network, called Tsikada, began deployments in 1976 with
Kosmos 883 and employs four orbital planes separated by 45 degrees. Moreover, the Tsikada orbital planes are carefully offset from the military satellites to maximize consolidated system effectiveness, i.e., minimize the mean time between satellite sightings. The Tsikada system is widely used by the Russian merchant marine which is equipped with Shkhuna receiving equipment which automatically computes the vessel's position. Originally, designed and manufactured by the Applied Mechanics NPO in Krasnoyarsk, both type of navigation satellites are now largely produced by the Polet PO in Omsk, where anannual production rate of ten spacecraft has been achieved. The navigational payloads were developed, in part, by the Institute of Space Device Engineering. By the end of 1994 more than 130 first generation satellites had been launched an average of five per year since
1967.

Despite their obvious similarities, Parus military navigation satellites are replaced at a much faster rate - about twice as often - than their Tsikada civilian cousins. During 1993-1994 two-thirds of the Parus network was replenished. Kosmos 2233 (9 February 1993) replaced Kosmos 2142 after 22 months in space, and Kosmos 2239 (1 April 1993) relieved Kosmos 2173 which had been on duty only 16 months. Later in the year according to Kettering Group observations, Kosmos 2195 failed after a little more than a year and was removed from the network. Its predecessor, Kosmos 2135, was then reactivated in early August while are placement satellite was prepared. Finally, on 2 November Kosmos 2266 was launched to assume the No. 1 Parus position. The only Parus satellite launched in 1994 was Kosmos
2279 on 26 April to replace the 26-month-old Kosmos 2180.

In the Tsikada system, two of the four active satellites were replaced. Surprisingly, Kosmos 2230 was launched on 14 January into the same orbital plane as Kosmos 2181, which had been the youngest Tsikada spacecraft with only 10 months in orbit. The next launch did not come for 18 months when Nadezhda 4 replaced the 4-year-old Nadezhda 2. The Nadezhda (Hope) name is now used whenever a Tsikada satellite carries a special transponder for use by the international COSPAS-SARSAT system for search and rescue of airmen and seamen in distress.

NAVIGATION

The Soviets advertised the existence of a navigation satellite system as long ago as 1966, but no Soviet satellite was specifically identified as having such a mission until the launch of Cosmos 1000 on March 31, 1978. Although no separate and distinctive name, such as Molniya and Meteor, has been given to later satellites in the series, a model of Cosmos 1000 was displayed at the 1979 Paris Air Show under the name of "Tsikada". Later, it was stated that the Tsikada navigation system was being created, based on Cosmos satellites, "to make it possible to determine the location of vessels at any point in the world's oceans, whatever the time of day and weather conditions." 52 The system would "shorten the duration of trans-oceanic voyages and give an annual economic benefit of hun­ dreds of millions of rubles."

In the same way that the U.S. Navy developed Transit first for use with its Polaris submarines, and then by stages extended the use to other naval vessels before declassifying it and making it available to civilian users, the Soviet system developed within the Cosmos program as a military system before being extended for use by their research and merchant vessels.

The first operational system providing rudimentary global cover­ age, established between December 1970 and December 1971, con­ sisted of three Cosmos satellites in near-circular orbits with periods close to 105 minutes and orbital inclinations of 74° with their orbit­al planes spaced at 120° intervals. Two replacement satellites were launched before this first system was phased out.

The second system, differing from the first in having an orbital inclination of 83° and a plane-spacing of 60°, was established be­ tween August 1972 and September 1973. Five replacement satel­ lites followed before Cosmos 800, which replaced Cosmos 663 in February 1976, was placed into an orbital plane 180° away. This had the effect of moving the orbital planes of the second operation­ al system away from those of the third system, which had been in­ troduced with Cosmos 700 in December 1974 and was being ex­ tended to a six-satellite system with 30° plane-spacing’s. The near- polar inclination of 83° meant, in effect, that satellites in orbital planes spaced 180° apart were virtually in the same orbital plane, but travelling in opposite senses. Thus it was only necessary to cover an arc of 180° with the orbital planes to achieve complete global coverage. Six more replacements followed before the second operational system was phased out, probably in the fall of 1979.

Cosmos 700 did not fit the general pattern of replacement, having its orbital plane offset by 20° from Cosmos 627. Cosmos 726 was also offset from the second system and 120° away from Cosmos 700. When Cosmos 775 was placed midway between them in Octo­ ber 1975, there was once more a three-satellite system with 60° plane-spacing’s.

Confirmation of the existence of two separate systems was ob­ tained from the monitoring of their radio transmission which, al­ though similar, had certain differences. The next launch in the series, Cosmos 778 in November 1975, signaled a further develop­ment. Placed midway between the planes of Cosmos 726 and 775, it marked the growth of the third operational system into a six-satel­ lite system with orbital planes spaced at 30° intervals which, as such, continues to this day.

The navigation message was decoded, almost completely, by the Kettering Group. 53 Transmissions on frequencies close to 150 MHz were shown to be 50 bits s-1, transitionally encoded, floating-point binary notation, providing an ephemeris and identity number for the transmitting satellite and almanacs for the other operational satellites in the system.

Cosmos 883, launched in December 1976, had its ascending node in the hemisphere opposite to those of the third operational system and took the identity number 11 (military satellites take identity numbers one through nine). It was followed by Cosmos 926, identity number 12, with its ascending node also in the opposite hemisphere and separated by 45° from Cosmos 883. All became clear with the launch of Cosmos 1000, number 13, a further 45° away, and the first to be specified as performing a navigation mission. The launch announcement also made reference to civilian usage. The civilian navigation system was completed by Cosmos 1092, number 14, an­other 45° away, establishing a four-satellite system with 45° plane-spacing. It has been observed that all civilian Cosmos navigation satellites transmit on 150.00 MHz.

The GLONASS System

The United States decided that it would be useful to possess a navigation satellite system which provided three-dimensional data and began development of the Navstar Global Positioning System. Similarly the Soviet Union decided to develop their three-dimen­ sional system, called GLONASS.

Since 1982, the Soviet Union has been conducting tests of such a system, employing passive range measurement. Although details of the system had been logged with the IFRB earlier that year, 54 the first launch was surprising—a triple payload in the Cosmos series launched by the Proton launch vehicle. From the initial parking orbit with a 51.6° inclination, the payloads were placed into 64.8° inclination, near-circular orbits, with periods close to 673 minutes. Cosmos 1413-1415 were not spaced regularly around the orbital plane, but drifted slowly apart from the common injection point. However, Cosmos 1414 made a small in-orbit maneuver revealing some propulsion capability and visual observations showed that Cosmos 1414 had a stable attitude.

The second launch in the series placed three more satellites into the same orbital plane, but the third launch, at the end of 1983, put Cosmos 1519-1521 into a plane separated by 120° from that of the first six. By the end of 1983, only Cosmos 1414 and 1491 had maneuvered to stabilize their positions in locations phased at 45° intervals.

Space Applications

navigation the tsikada system 1981-1987

Replacements of the Cosmos satellites of the civil "Tsikada" navigation system were launched as required during 1984-1987. The civil satellites are replaced less frequently than their military counterparts, suggesting that they offer a lower degree of precision to the user. There is also evidence that the power outputs of these satellites are allowed to deteriorate to lower levels before replace­ ment is considered. 118

The operational civil system consists of four satellites in orbital planes spaced at 45° intervals in right ascension. Each plane takes a specific identity number from 11 through 14. Satellites which have been replaced and then subsequently re-activated to provide a back-up service and those which have just been launched and are in the pre-operational check-out phase may take identity numbers of 15 upward. For instance, shortly after launch, Cosmos 1727 had the identity number 16 but assumed identity number 12 on replac­ ing Cosmos 1506 as the operational satellite in that plane. 119 In July 1987 a civil navigation satellite, observed to be transmitting five parameter blocks, was identified as the replaced Cosmos 1383 which had identity number 11 when operational but then assumed identity number 15. This implies that the "temporary" identity numbers are n + 4, where n is the plane identity number for an operational satellite.

All satellites transmit a 6,000-bit navigation message at a rate of 50 baud on a frequency of 150.00 MHz. A near-complete description of that message has been published elsewhere. 120

Kettering Group observations during 1986 from the Falkland Is­ lands and Western Australia established that the civil navigation satellites transmit continuously. 12l

Table 24 lists the Cosmos satellites in the civil "Tsikada" naviga­ tion system from 1984 through 1987.

Apogee and perigee heights in kilometers, inclination in degrees, and orbital periods in minutes.

Orbital data, which may differ from that given in the Master Log has been computed from two line orbital element sets provided by NASA's
Goddard Space Flight Center.

Numbers preceded by # indicate the identity numbers referred to in the satellites' navigation messages.

Numbers in brackets are the Cosmos numbers of satellites replaced by those listed.

Cosmos 1861 transmitted a navigation message for only a few days following its launch. For further details refer to the section on Amateur
Radio in this chapter.

Table prepared for the Congressional Research Service by G. E. Perry.

Cosmos 1383 was nearly two years old when it was replaced by Cosmos 1553, which did not carry Cospas search and rescue equip­ ment (see next section) to replace that onboard Cosmos 1383. The second launch of 1984, Cosmos 1574, carried the third Cospas trans­ ponder and replaced Cosmos 1339 after 28 months. Cosmos 1655, the only launch in 1985, replaced Cosmos 1447 after 26 months but, like Cosmos 1553, did not carry Cospas equipment to replace that onboard the older satellite. Observations made during the early part of 1988 suggest that all three Cospas transponders were still operating, although their host satellites had been replaced as navi­ gation satellites.

The two launches in 1986 were routine replacements for satel­ lites which had been in orbit for 27 months and two and one half years respectively. Cosmos 1816 replaced Cosmos 1574 in January 1987 after 31 months and did not have Cospas equipment to replace that on Cosmos 1574. Cosmos 1861 appeared to have been a replace­ment for Cosmos 1727 after only 17 months but, as described in the section above dealing with amateur radio, also carried the RS10 and RS11 transponders. It could be that it is an example of in-orbit storage, analogous to the U.S. SOOS (Stacked Oscars On Scout) pro­ gram and was launched primarily to take the amateur radio equip­ ment into space without the delay of waiting for the need to re­ place an operational satellite. After several days of check-out, during which it transmitted as a navigation satellite on several oc­ casions, the navigation transmission on 150.00 MHz was placed in the stand-by mode.

At the end of 1987 the four operational "Tsikada" satellites were Cosmos 1791 (13), Cosmos 1727 (24), Cosmos 1655 (31) and Cosmos 1816 (11) in planes 11 through 14 respectively (numbers in paren­ theses are the number of months each satellite had been in orbit at that date).

Table 25 shows the replacement sequence of the Cosmos satel­ lites in the civil "Tsikada" navigation system in their respective planes and table 26 shows the right ascensions of the ascending nodes for the operational satellites in the system as of January 10, 1988.